Cairene Crusade

The Cairene Crusade was a crusade called by Pope Paschal II against the Fatimid Caliphate in 1094 with the goal of securing the right of Christian pilgrims to travel to holy places in Egypt. The Kingdom of England was the only European country to take part in the crusade, and Duke Robert of Normandy led a crusading army of Normans and Bretons from France to take part in the crusade against the Fatimids of Egypt. The Normans captured Alexandria and Cairo from the Fatimids, fulfilling the goal of conquering Cairo in addition to the capture of Alexandria, and it was just a matter of holding the cities after the crusade ended.

Background
The Fatimid Caliphate seized power in Egypt in 969 after evicting the Abbasid Caliphate from North Africa, implementing Shia Muslim rule in Egypt, but also offering religious freedom to Christians, Jews, and other minorities. The Seljuk Empire's 1073 capture of Jerusalem under Tutush I of Damascus led to fears of the persecution of the religious minorities by the Turks, and it led to Christendom hungering for the recapture of the holy lands from the Muslims. The idea of a "crusade", a Christian holy war, became popular due to the perceived Muslim persecution of Christians, and King William the Conqueror suggested that Pope Paschal II could call a crusade against the Muslims of Cairo. In 1094, Pope Paschal called a crusade for Cairo, and the English noble Robert of Normandy decided to join the crusade.

Embarkation
Deciding to join a crusade was easy, but actually embarking on one was tougher. Robert was already in command of an army, having subjugated Brittany with his conquest of Rennes in 1084, but his army was not large enough to embark on a campaign against a nation such as the powerful Fatimid Caliphate. Robert decided to hire some mercenaries to join his army, hiring crusader sergeants and crusader mailed knights to accompany his Anglo-Norman army. He also hired some cogs, and the fleet left Brittany for Egypt in 1096. His fleet took a long time to reach Egypt, arriving in 1110.

Capture of Alexandria
The crusaders were joined by two groups of Sudanese mercenaries on their arrival, Robert knowing that only coin would motivate Egyptians to betray the Fatimids and side with his invading army. His army encamped outside the major port city of Alexandria, defended by Sultan al-Mustansir Billah himself. The Fatimids foolishly attacked the numerically-superior crusading army, leading to a crusader victory against the Saracens and the capture of Alexandria shortly after. The crusaders massacred over 3,000 people when they entered Alexandria, but they rebuilt the city and constructed a chapel and some other facilities to help in the assimilation of the Egyptian people.

Successful end
In 1122, after years of suppressing dissent in Alexandria and recuperation from its capture, the crusading army decided to make the final push on Cairo. Robert of Normandy feared that Crown Prince Moussa and al-Fayed of Kharga would lead their armies to relieve the city, but Robert's siege was unmolested. He succeeded in his storming of Cairo, and the crusaders massacred 7,170 people after entering the former Fatimid capital. The crusade met its bloody end with Cairo's fall to the crusaders, and the Pope financially rewarded the Kingdom of England for its role in the conquest of Cairo.